Power Comes From The Ground

Power comes from your muscles. The ground is just there doing nothing.
Now you you can think about which muscles are creating that power.
 
Curious said:
Power comes from your muscles. The ground is just there doing nothing.
Now you you can think about which muscles are creating that power.
Click to expand...
You will never, ever get as much RHS from keeping two feet on the ground than by letting one of them leave it. Try it as many times as you like.
 
Rosstour said:
Haha thanks

To that point, serve may be the one exception. But even the best platform servers of the OE get/got off the ground.
Click to expand...
What do you think gets you off the ground on the serve or with any type of jumping? Remember, the ground is just being there doing nothing.
 
shug said:
Maximizing Power
Click to expand...
Yep. One of the biggest severs ever had a force against the ground of double his weight iirc. That was roscoe tanner and here the TT morons are just missing basic physics as mentioned in this analysis vid:

ESPN Roscoe Tanner - Fastest Tennis Serve - Ariel Dynamics

Ariel Dynamics, Inc. is a leading innovator and service provider in the fields of Athletics, Biomechanics, and Sports and Rehabilitative Medicine. It performs individual motion analysis studies, known as the Ariel Performance Analysis System (APAS), and manufactures computerized...
www.arielnet.com www.arielnet.com

Roddick said himself the key was the legs
 
Shroud said:
Yep. One of the biggest severs ever had a force against the ground of double his weight iirc. That was roscoe tanner and here the TT morons are just missing basic physics as mentioned in this analysis vid:

ESPN Roscoe Tanner - Fastest Tennis Serve - Ariel Dynamics

Ariel Dynamics, Inc. is a leading innovator and service provider in the fields of Athletics, Biomechanics, and Sports and Rehabilitative Medicine. It performs individual motion analysis studies, known as the Ariel Performance Analysis System (APAS), and manufactures computerized...
www.arielnet.com www.arielnet.com

Roddick said himself the key was the legs
Click to expand...
Rodrick also had the fastest elbow acceleration of all time

Who has a better serve, Sinner or Fils?
 
No clue. Tennis sucks these days. is fils Monfils or someone else?

Roddick also had a super flexible shoulder. But he himself says the serve comes from the legs.
 
Rosstour said:
You will never, ever get as much RHS from keeping two feet on the ground than by letting one of them leave it.
Click to expand...
Leave how? Just lift it up, or push off?
Which one will transfer more momentum?

As for the op, power comes from many places as a sum of parts. From the ground up is one of them. This is undeniable.
 
Curious said:
I’m keen to learn what the ground does exactly. Never understood the ground reaction force if that’s what you meant.
Click to expand...

So, one has to understand first is the first law of motion (law of inertia). It states that any object remains with its current motion (still or constant) speed unless an external force applies.

But what happens when an internal force (muscle) moves a part of an object (the body)? The first law applies. So, here it's my experiment. Go to an office chair that has a rotating axis, and stand upong your knees. Grab the racquet and swing. You'll find that you end up looking at the side of the hand you used to do the swing. Why? for the hand to swing, your body needed to compensate rotating in the other direction. Remember that there are no EXTERNAL forces applied to the body, because the rotating axis has very low friction. Of course what is missing that makes your swings on court be stable is the connection of your moving limbs with the ground though the core, hips, and legs.

So, the ground does nothing but stay still, but that's actually a lot. Standing still allows to keep balance, provide momentum to the body. How it's done? Its the only thing that can provide EXTERNAL forces to us during tennis play. Of course, we provide internal forces that make our feet collide into the ground: motions like running, jumping, but also swinging a racquet, we achieve by moving against a plane of reference that stays still. From our point of view we could even say that while doing those actions we are "moving" the earth (in the opposite direction).

So about reaction forces. That is the third law: Forces don't exist alone. When a body exerts a force against another, there is a reaction force; but these are interchangeable. That applies not only to bodys in direct contact (example: your weight times acceleration is the force that you apply to your chair/coach, that is applied back to you), but also to others such as planets and satellites (earth and the moon). Forces are equal in magnitude but opposite. In sports, for a reaction force from the ground to appear, we need to be active; that means, pushing with the feet. That is how internal forces (muscles) make feet collide into the ground and hence make the body move.

How this applies to tennis? Well, there is no action taken in tennis except standing still (and even that) that is not ground up, just because when motion exist, it involves doing it with respect to some reference. When swinging, we first need to grab some momentum (impulse) from the ground, into the body. Once we are handling that, we can start to swing. That swing will prevent the body to actually do the forward momentum and rotation that was started from the legs. That is not done consciously. Brain has a lot of information of the requirements for the body to keep balance while doing certain movements.
 
So I said all actions come from the ground, but there are some exceptions that in some sense don't need the ground.

Actions that go purelly from up to down. Example, pulling from a rope to open a courtain. There's no involvement from the ground there as it concerns internal forces from the body transferring to the ground. That applies to (some extent) to shots like the slice if we remove the forward momentum transfer and the fact that we put the racquet in a high position to start with. Other actions are the *initial* part of the swing of a bat or a golf club, that is initially from a high position towards a lower position. Forces tranferred through the body and onwards would come later.
 
High to low is usually considered potential energy (edit word missed out)

Iirc ground reaction forces are something like 3x body weight in running, 5 x in jumping, landing when bowling in cricket 9x body weight all through 1 foot initially.

Ben Hogan wasn't wrong the secret is in the dirt.
 
ppma said:
So, one has to understand first is the first law of motion (law of inertia). It states that any object remains with its current motion (still or constant) speed unless an external force applies.

But what happens when an internal force (muscle) moves a part of an object (the body)? The first law applies. So, here it's my experiment. Go to an office chair that has a rotating axis, and stand upong your knees. Grab the racquet and swing. You'll find that you end up looking at the side of the hand you used to do the swing. Why? for the hand to swing, your body needed to compensate rotating in the other direction. Remember that there are no EXTERNAL forces applied to the body, because the rotating axis has very low friction. Of course what is missing that makes your swings on court be stable is the connection of your moving limbs with the ground though the core, hips, and legs.

So, the ground does nothing but stay still, but that's actually a lot. Standing still allows to keep balance, provide momentum to the body. How it's done? Its the only thing that can provide EXTERNAL forces to us during tennis play. Of course, we provide internal forces that make our feet collide into the ground: motions like running, jumping, but also swinging a racquet, we achieve by moving against a plane of reference that stays still. From our point of view we could even say that while doing those actions we are "moving" the earth (in the opposite direction).

So about reaction forces. That is the third law: Forces don't exist alone. When a body exerts a force against another, there is a reaction force; but these are interchangeable. That applies not only to bodys in direct contact (example: your weight times acceleration is the force that you apply to your chair/coach, that is applied back to you), but also to others such as planets and satellites (earth and the moon). Forces are equal in magnitude but opposite. In sports, for a reaction force from the ground to appear, we need to be active; that means, pushing with the feet. That is how internal forces (muscles) make feet collide into the ground and hence make the body move.

How this applies to tennis? Well, there is no action taken in tennis except standing still (and even that) that is not ground up, just because when motion exist, it involves doing it with respect to some reference. When swinging, we first need to grab some momentum (impulse) from the ground, into the body. Once we are handling that, we can start to swing. That swing will prevent the body to actually do the forward momentum and rotation that was started from the legs. That is not done consciously. Brain has a lot of information of the requirements for the body to keep balance while doing certain movements.
Click to expand...
I still don’t quite get it. I can’t imagine the ground just staying still there exerting some force at my feet when I jump. It sounds to me that when the calf muscles contract they pull the heel off the ground (Achilles tendon pulling the heel up), the whole body starts moving up gaining momentum and if the contraction is fast and powerful enough this momentum makes the body airborne.

The feet pushing the ground makes the ground push the feet in return doesn’t sound plausible.
 
Last edited:
Curious said:
The feet pushing the ground makes the ground push the feet in return doesn’t sound plausible.
Click to expand...
Yeah it's hard to understand it (though it's easier to imagine). It's just a property of our physical world. A given. We don't question a given. It's like trying to understand why's. Usually not possible. Just accept them.
 
why are we still talking about this. go out hit some balls, it's obvious the power doesn't come from the ground.

btw El Cap is trolling.
 
Curious said:
I still don’t quite get it. I can’t imagine the ground just staying still there exerting some force at my feet when I jump. It sounds to me that when the calf muscles contract they pull the heel off the ground (Achilles tendon pulling the heel up), the whole body starts moving up gaining momentum and if the contraction is fast and powerful enough this momentum makes the body airborne.

The feet pushing the ground makes the ground push the feet in return doesn’t sound plausible.
Click to expand...
The way you describe it is half of the story.

So, momentum is described as the amount of movement. Mass times velocity. So let's put you hace 75kg of maas. Earth has 6 times 10^24 kg. For you to develop a speed of 1m/s you pushed the Earth to a velocity of around 9 times 10^-22 m/s, which of course is almost unmeasueable

Force is somewhat of an abstraction. If you jump all the work that the muscles produce go at the end to your soles. There you have a pressure, that can be measure there, but also on the terrain. I believe pressure is a little bit more easy to understand. The addition of all those pressures in different spots give as a result a total force that can be decomposed in two masses and accelerations (of your body and Earth).
10sbeast888 said:
it's obvious the power doesn't come from the ground.
Click to expand...
Yeah that's true. Power come from the compression or extension of the sarcomeres fueled by glucogen. What comes from the ground is momentum.
 
Anyone thinks the fh starts from the ground. Go out there and vid. Your stroke will never look half as good as the girl on heels.
 
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